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The Crust and Upper Mantle Beneath the Sea. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm013p0556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Seismic Model of the Atlantic Ocean. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm013p0220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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North Pacific Sediment Layers Measured by Seismic Profiling. THE CRUST AND UPPER MANTLE OF THE PACIFIC AREA 2013. [DOI: 10.1029/gm012p0147] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Stratigraphy and structure along a continuous seismic reflection profile from Cape Hatteras, North Carolina, to the Bermuda Rise. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jz072i008p02107] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Mid-Atlantic Ridge between 22° and 23° north latitude and the tectonics of mid-ocean rises. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb073i004p01279] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Tectonic wedging in the forearc basin: Accretionary prism transition, Lesser Antilles forearc. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb094ib08p10549] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Seismic stratigraphy, lithostratigraphy and paleosedimentation patterns in the North American Basin. ACTA ACUST UNITED AC 1979. [DOI: 10.1029/me003p0058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Eastern Atlantic Continental Margin: Some Results of the 1972 Cruise of the R.V. Atlantis II. Science 1972; 178:298-301. [PMID: 17735476 DOI: 10.1126/science.178.4058.298] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A geophysical survey of the southeastern Atlantic Ocean has been made as one of the programs of the International Decade of Ocean Exploration. A large ancient delta of the Orange River and a diapiric field off Angola were mapped. Both features were initiated during early stages of the separation of Africa and South America, and both may be potential sources of oil.
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Abstract
Layer A and its correlative layer A" in the Caribbean have been interpreted as chert layers produced by Eocene volcanism. Exposures of Eocene volcanic rocks in Puerto Rico and the Dominican Republic may represent layer A interbedded with coarser volcanic debris and preserved near early Tertiary volcanic centers.
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Abstract
Evidence from leg 2 of the Deep Sea Drilling Project suggests a constant spreading rate for the floor of the North Atlantic over the past 80 million years; a major lowering of the carbonate dissolution level during the early Pliocene; and an early to middle Eocene age for horizon A.
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Magnetic Anomalies and Seafloor Spreading Rates in the Northern South Atlantic. Nature 1970; 226:328-30. [PMID: 16057239 DOI: 10.1038/226328a0] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 12/05/1969] [Indexed: 11/08/2022]
Abstract
A geomagnetic profile across the northern South Atlantic yields spreading rates for the last 70 m.y. which vary from 1.6 to 2.0 cm/year. There is evidence for three regional discontinuities in the spreading history of the South Atlantic.
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Abstract
Horizon beta is a subbottom reflector in the North Atlantic deep ocean sediments that extends over a large portion of the North America basin. Cores from an outcrop of beta contained shallow-water Aptian-Albian sediments and deep-water Cenomanian sediments. A core near an outcrop of a deeper horizon, horizon B, contained shallow-water Lower Cretaceous (Barremian-Hauterivian) sediments. These cores can be interpreted to support extensive subsidence of the eastern portion of the basin in early Cretaceous time. It is equally likely that the shallow-water deposits are a result of sediments slumping into an already deep basin. A reconciliation of these interpretations depends upon the JOIDES project.
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Abstract
Palynology was used for dating a pre-Pleistocene deep-sea organic lutite layer situated stratigraphically near seismic horizon beta, below horizon A. The spores and pollen are closely identified, quantitatively, with nonmarine and marine Middle Cretaceous assemblages (Albian-Cenomanian) on the continents, an age designation that is confirmed by the occurrence of dinoflagellate cysts, acritarchs, foraminifers, and coccoliths in the investigated cores. The abundance of these well-preserved, land-derived assemblages in an area far removed from a source suggests some tectonic displacement since their deposition.
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Association of a seismic reflector and upper cretaceous sediment in the Bay of Biscay. ACTA ACUST UNITED AC 1968. [DOI: 10.1016/0011-7471(68)90083-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ocean bottom photographs in the area of the oldest known outcrops, north atlantic ocean. Proc Natl Acad Sci U S A 1968; 61:787-93. [PMID: 16591708 PMCID: PMC305395 DOI: 10.1073/pnas.61.3.787] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Geophysics: Continental Drift Comes True. Nature 1967. [DOI: 10.1038/2151061a0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Ten magnetic profiles across the mid-Atlantic ridge near 27 degrees N show trends that are parallel to the ridge axis and symmetrical about the ridge axis. The configuration of magnetic bodies that could account for the pattern supports the Vine and Matthews hypothesis for the origin of magnetic anomalies over oceanic ridges. A polarity-reversal time scale inferred from models for sea-floor spreading in the Pacific-Antarctic ridge and radiometrically dated reversals of the geomagnetic field indicates a spreading rate of 1.25 centimeters per year during the last 6 million years and a rate of 1.65 centimeters per year between 6 and 10 million years ago. A similar analysis of more limited data over the mid-Atlantic ridge near 22 degrees N also indicates a change in the spreading rate. Here a rate of 1.4 centimeters per year appears to have been in effect during the last 5 million years; between 5 and 9 million years ago, an increased rate of 1.7 centimeters per year is indicated. The time of occurrence and relative magnitude of these changes in the spreading rate, about 5 to 6 million years ago and 18 to 27 percent, respectively, accords with the spreading rate change implied for the Juan de Fuca ridge in the northeast Pacific.
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Abstract
Magnetic boundaries parallel the continental slope and separate undisturbed from disturbed magnetic regions on both sides of the North Atlantic. The boundaries lie 2000 to 2500 kilometers from the axis of the mid-Atlantic ridge and roughly equidistant from it. The undisturbed zone, lying on the continental side of the boundaries, may reflect the long period of no reversals in magnetic polarity that occurred during the late Paleozoic.
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Abstract
An abrupt change in sediment thickness between the crests and flanks of the mid-ocean ridges can be interpreted as a major discontinuity in the rates either of spreading of the sea floor or of accumulation of sediment. The preferable interpretation of the data is that the process of spreadig of the sea floor is intermittent and that the present cycle of spreading commenced around 10 million years ago. following a long period Of quiescence during which most of the observed sediments were deposited.
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Abstract
The technique of using magnetic-tape recorders and atomic frequency standards to operate two widely separated radio telescopes as a phase-coherent interferometer when the stations have no radio-frequency connecting link has been successfully tested at the National Research Council of Canada's Algonquin Radio Observatory.
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Abstract
A continuous seismic profile across the Blake Outer Ridge reveals clear evidence of a structural origin for the ridge. A ridge core separates distinctive regions of structure east and west of the crest and does not support a theory of depositional origin. The presence of horizon A continuously beneath the ridge rules out faulting or folding involving basement rocks. Gravity tectonics are suggested as the mechanism for formation of the ridge after the deposition of the sediments above horizon A.
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Abstract
Cores recovered from horizon A are Late Cretaceous (Maestrichtian) in age and consist o alternating layers of calcareous turbidites and "red clay." The presence of red clay suggests that the water depth in this area during Cretaceous time was at least as great as at present-more than 5100 meters. A middle Cretaceous (Cenomanian) core consisting of interbedded sand and gravel and light-to-dark-gray lutite was taken in the same area from a layer stratigraphically below the horizon; the presence of hydrogen sulfide and iron sulfide may indicate anaerobic conditions that may be attributable to local ponding of sediment in Cenomanian time.
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